(a) Field of the Invention
A direct current to direct current (DC-DC) converter and a light emitting diode driving device including the same are provided.
(b) Description of the Related Art
A light emitting diode (hereinafter, referred to as an “LED”) is primarily used as a light source in various display devices. While a known cold cathode fluorescent lamp (hereinafter, referred to as a “CCFL”) requires an inverter which is driven by a high-frequency alternating current (“AC”) current, the LED requires a converter which is driven by a DC current.
Unlike the inverter used in the CCFL, a DC-DC converter used in the LED includes a rectifier circuit part for generating the DC current. Further, an LED driving device may be operated by a pulse width modulation (hereinafter, referred to as a “PWM”) dimming control method or an analog dimming control method in order to control luminance of the LED. The PWM dimming control method controls a brightness of the LED by controlling a ratio of on-off times of the LED according to a PWM signal. For example, when the PWM signal having the ratio of the on-off times of 4:1 is supplied to the LED, the brightness of the LED may be 80% of a maximal brightness. The analog dimming control method controls the brightness of the LED by controlling a current amount supplied to the LED.
The DC-DC converter used in the LED of the display device may be a boost converter which receives a low DC voltage to output a high DC voltage. For example, a DC voltage of 15 volts (V) to 30 V may be changed to a DC voltage of 100 V to 280 V by using the DC-DC converter. Since the DC-DC converter significantly changes a voltage level, a voltage stress on a circuit element configuring the DC-DC converter may be high, an electromagnetic interference (“EMI”) may occur, and efficiency of the converter may be reduced.